POS0619 HIGH SERUM CXCL10 PREDICTS NEW ONSET OF SYSTEMIC SCLEROSIS-INTERSTITIAL LUNG DISEASE
Authors: Y. Al-Adwi, I. M. Atzeni, B. Doornbos- van der Meer, M. Van der Leij, B. J. Kroesen, A. J. Stel, H. Van Goor, T. J. Gan, W. Timens, J. Westra, D. J. Mulder
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Systemic sclerosis-interstitial lung disease (SSc-ILD) is a severe complication that affects most SSc patients causing one-third of SSc-related deaths [1]. There is an unmet need for predictive biomarkers of ILD to identify patients at risk, prior to clinical manifestation. Activated IFN-induced chemokines and proteins are implicated in the early inflammatory phase of SSc-ILD [2]. CXCL10 is an IFN-induced chemokine that is important in the chemoattraction of inflammatory cells in SSc-affected tissue [3,4]. <h3>Objectives</h3> We investigated CXCL10 serum levels in SSc, SSc-ILD, and healthy controls (HCs) to understand whether CXCL10 levels differ between groups and potentially play a role in ILD pathogenesis. We also sought whether CXCL10 levels in serum mirror those in the lungs to investigate whether systemic levels reflect those of the affected organ locally. The transcriptomic study investigated CXCL10 expression in inflammatory SSc-ILD lung sections compared to fibrotic sections to show whether CXCL10 is more prominent in early disease. We also assessed whether CXCL10 could serve as a predictive biomarker for the new onset of SSc-ILD. Finally, to better comprehend the clinical observations, <i>in vitro</i> studies aimed to reveal the inflammatory/fibrotic effects of local and systemic fluids of SSc-ILD patients compared to SSc without ILD and controls. <h3>Methods</h3> One-hundred sixty-five SSc patients (SSc-ILD = 41) and 13 age- and sex- matched HCs were retrospectively followed from 2013 to 2020. Furthermore, 15 SSc patients (SSc-ILD = 7) were prospectively recruited for bronchoalveolar lavage (BAL) procedure. CXCL10 mRNA and protein levels were measured on various levels (serum, BAL, and SSc-ILD lung tissues) by ELISA and nanoString transcriptomic assay. Spearman's correlations were performed between CXCL10 levels in serum and lungs. Kaplan-Meier analyses were performed to evaluate predictability of SSc-ILD using CXCL10 levels at baseline. Human primary lung fibroblasts were treated with BAL fluid or serum from SSc without ILD or SSc-ILD patients. After stimulation, inflammatory (IL-6 and CXCL10)/fibrotic (α-SMA and TGF-β) genes were assessed using qPCR. <h3>Results</h3> At baseline, serum CXCL10 was significantly higher in SSc-ILD patients compared to SSc without ILD [Median (IQR): 126 (66-282) vs 79 (50-122), p = 0.004] and HCs [Median (IQR): vs. 4 (4-9), p &lt; 0.0001]. BAL fluid CXCL10 levels in SSc-ILD patients were not significantly higher than those in SSc without ILD [Median (IQR): 457 (42-725) vs 134 (72-333), p = 0.2). However, BAL CXCL10 levels significantly correlated with serum levels (r = 0.7, p = 0.007). The nanoString showed that CXCL10 gene expression is significantly higher in inflammatory lung tissue compared to fibrotic tissue (fold change = 2.3, p = 0.029). Kaplan-Meier survival analysis (Figure 1) revealed that CXCL10 levels &gt;3<sup>rd</sup> quartile at baseline in SSc patients significantly predicted new onset of ILD (p = 0.023). The <i>in vitro</i> studies showed that CXCL10 and IL-6 were significantly overexpressed in lung fibroblasts treated with SSc-ILD BAL fluid or serum compared to SSc without ILD [(CXCL10: p = 0.0043; p = 0.0087), (IL-6: p = 0.0022; p = 0.0043), respectively) and controls (all: p = 0.0022). On the contrary, TGF-β and α-SMA expression did not change after treatment in all groups. <h3>Conclusion</h3> CXCL10 is a potential predictive biomarker for new onset of ILD in SSc patients. Further longitudinal studies with larger sample sizes are needed to verify the capability of CXCL10 to predict ILD. Additionally, our nanoString and <i>in vitro</i> data suggest that CXCL10 may play a significant role in the early development of SSc-ILD which might be amenable to therapeutic interventions. <h3>References</h3> [1]Volkmann et al, Journal of Sclero and Rel Dis. 2021; 10.1177/2397198320915042 [2]Wu et al, <i>Frontiers in Immunology</i>, 2013; 10.3389/fimmu.2013.00266 [3]Fujii, et al, <i>J Dermatol Sci</i>, 2004; 10.1016/j.jdermsci.2004.03.001 [4]Antonelli <i>et al</i>, <i>Rheumatology</i>, 2008; 10.1093/rheumatology/kem313 <h3>Acknowledgements</h3> This collaboration project is co-financed by the Ministry of Economic Affairs and Climate Policy by means of the PPP-allowance made available by the Top Sector Life Sciences &amp; Health to stimulate public-private partnerships. The Health-Holland communication toolkit is available on "Communication Toolkit" | Health-Holland (health-holland.com). Part of this project is funded by Sanofi Genzyme. <h3>Disclosure of Interests</h3> Yehya Al-Adwi: None declared, Isabella M. Atzeni: None declared, Berber Doornbos- van der Meer: None declared, Marcel Van der Leij: None declared, Bart-Jan Kroesen: None declared, Alja J. Stel: None declared, Harry van Goor: None declared, Tji-Joong Gan: None declared, Wim Timens: None declared, Johanna Westra: None declared, Douwe J Mulder Grant/research support from: Dr DJ Mulder as an employee of the UMCG received research grants from Sanofi which were paid to the UMCG.